Description

1.Features and Scope of Application

Zinc Oxide Desulfurization Adsorbent, developed by the Northwest Research Institute of Chemical Industry, is applicable to desulfurization of residue cracking gases or syngas and purification of feed gases for organic synthesis processes. It is suitable for both higher (350--408) and lower(150--210) temperature use. It can convert some simpler organic sulfur while absorbing inorganic sulfur in gas stream.

Main reaction of the desulfurization process is as follows:

(1) Reaction of zinc oxide with hydrogen sulfide

H2S+ZnO=ZnS+H2O

(2) Reaction of zinc oxide with some simpler sulfur compounds in two possible ways:

T306 is an ideal desulfurization adsorbent for deep purification cases, especially those at higher temperature (350--400).

2.Physical Properties

Appearance

white or light-yellow extrudates

Particle size , mm

Φ4×4--15

Bulk density, kg/L

1.01.3

3.Quality Standard

crushing strength, N/cm

≥50

loss on attrition,

≤6

Breakthrough sulfur capacity, wt

≥28350

≥15220

≥10200

4.Normal Operation Condition

Feedstock : synthesis gas , oil field gas, natural gas, coal gas. It can treat gas stream with inorganic sulfur as high as 2-3g/m3 with satisfactory purification degree. It can also purify gas stream with up to 20mg/m3 of such simpler organic sulfur as COS to less than 0.1ppm.

Normal operation condition is as follows:

Pressure, MPa

ambient to 4.0

Temperature,

180-400

Space velocity, h1

1000-2000gas

Sulfur in feed gas, mg/m3

1-20 (≤200)

20-100 (≤250)

Sulfur in treated stream, ppm

max0.1

Saturation sulfur capacity, wt%

min30(400)

5.Loading

Loading depth: Higher L/D (min3) is recommended. Configuration of two reactors in series can improve utilization efficiency of the adsorbent.

Loading procedure:

(1)Clean the reactor before loading;

(2)Put two stainless grids with smaller mesh size than the adsorbent;

(3)Load a 100mm layer of Φ1020mm refractory spheres upon the stainless grids;

(4)Screen the adsorbent to remove dust;

(5)Use special tool to ensure evenly distribution of the adsorbent in the bed;

(6)Inspect uniformity of the bed during loading. When inside-reactor operation is needed, A wood plate should be put on the adsorbent for the operator to stand upon.

(7)Install A stainless grid with small mesh size than the adsorbent and a 100mm layer of Φ2030mm refractory spheres at the top of the adsorbent bed so as to prevent entrainment of the adsorbent and ensure even distribution of the gas stream.

Note: Evenly distribution of the adsorbent is essential to its efficient operation, which should be paid close attention to.

6.Start-up

(1)Replace the system by nitrogen or other inert gases until oxygen concentration in the gas is less than 0.5%;

(2)Preheat the feed stream with nitrogen or feed gas under ambient or elevated pressure;

(4)Adjust the pressure steadily until the operation pressure is attained.

(5)After pre-heating and pressure elevation, the system should first be operated at half load for 8h. Then raise the load steadily when operation becomes stable till full-scale operation.

7.Shut-down

(1)Emergent shut-down

Cut feed gas (oil) supply. Close inlet and outlet valves. Keep the temperature and pressure. If necessary ,use nitrogen or hydrogen-nitrogen gas to maintain the pressure to prevent negative pressure.

(2 ) Change-over of desulfurization adsorbent

Close inlet and outlet valves. Steadily lower the temperature and pressure to ambient condition. Then isolate the desulfurization reactor from the production system. Replace the reactor with air until oxygen concentration of 20 is attained. Open the reactor and unload the adsorbent.

(3) Equipment maintenance (overhaul)

Observe the same procedure as shown above except that pressure should be lowered at 0.5MPa/10min and temperature lowered naturally.

The unloaded adsorbent shall be stored in separate layers. Analyze the samples taken from each layer to determine status and service life of the adsorbent.

8.Transportation and storage

(1)The adsorbent product is packed in plastic or iron barrels with plastic lining to prevent moisture and chemical contamination.

(2)Tumbling, collision and violent vibration should be avoided during transportation to prevent pulverization of the adsorbent.

(3)The adsorbent product should be prevented from contact with chemicals during transportation and storage.

(4)The product can be stored for 3-5 years without deterioration of its properties if appropriately sealed.

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